Tape measure beam antenna and fox hunt update

I totally screwed up by not noticing my mouser order was placed on back order (due to one unneeded part (for this project anyway)). So the SMA Female connectors will not be here until first part of next week. I checked Altex and Intertex Electronics to see if they stocked the SMA Female connectors we need, and they don't. Everything else is in and we have materials to build up to 6 tape measure beam antennas. I do have SMA Male and BNC Male connectors for the LMR-100 coax.

Total cost of parts for one antenna is ~$14.13 excluding tax, shipping, and misc materials/supplies. So we'll just round it up to an even $20.

As far as a date for the fox hunting, my next free Saturday is Oct 27.... Not sure if that works for y'all or not, or what days/times you guys want to do the fox hunting on. So please feel free to reply with dates/times that'll work for you. Also note, that you don't have to be a ham to participate, but you do need a receiver that can pickup FM in the range of 144 MHz to 148MHz (i.e. a scanner should work just fine). Additionally depending on how we do the fox hunting we may want to do it in teams of 2 for safety purposes and to get additional people to participate. On the day of the transmitter hunt, I think we should be able to do 2 or maybe even 3 hunts, which should give each person on a team a chance to handle the gear on their own.

Do we want a lot of people? I know a mailing-list full of people that
would probably like to participate.

Im going to guess that there are four teams now. Jeremy, KC, Matt, and I.
If each team has 2-3 people then thats 8-12 people. Do we want more
people/teams? I can maybe get 4 more people but i don't know if any of
them are Hams. Maybe we can start recruiting more Ham operators on the
Wednesday net.
> --
> You received this message because you are subscribed to the Google Groups
> "10BitWorks" group.
> To post to this group, send email to sa-hack...@googlegroups.com.
> To unsubscribe from this group, send email to
> sa-hackerspac...@googlegroups.com.
>
>

No worries on the Mouser order Jeremy; you’re allowed to screw up just like the rest of us!

Sat 27 October is fine with me.

I’d like to have you make me two custom cables. A SMA male<->BNC male to go from my HT to my offset attenuator http://www.west.net/~marvin/k0ov.htm , and a BNC M<-> loose ends to attach to my antenna. We can figure out the lengths on Saturday.

Daydreaming again……. We could make our fox hunt a real challenge by incorporating two foxes and geocache elements as well. Follow me now…..

Each team consists of fox hunters AND geocachers.

1)Start – 1st fox is activated, geocachers are given coordinates to 1st geocache.

2)Fox hunters hunt fox, cachers hunt cache.

3)1st geocache holds log book, frequency of second fox, and phone number for 1st arriving team to call to activate fox #2. Each geocache team signs log, and calls their fox hunt partners to inform them of the fox #2 frequency

4)1st fox location holds a log and coordinates for geocache #2. Fox hunters arriving at fox #1 sign log book and phone their geocache partners to give them the coordinates for geocache #2.

@Mike: We'll probably want to keep this first one smallish and simple, especially since we only have one beacon, and it's our first try...

@Matt: Sure, no problem, and that offset attenuator looks really neat, and simple. Looks like xtal oscillator with diode mixer. Ah, just found more info: http://www.homingin.com/joek0ov/offatten.html And that sounds like a really fun game.

anyone here ever do an rogaining? http://en.wikipedia.org/wiki/RogainingIt's similar to what Matt has described except that all checkpoints
are known ahead of time. The challenge is more about land navigation
rather than radio hunts. I did one a couple of years ago one someone's
50+ acre tract in Helotes. The topology there was so varied (steep
800' hills, brush, lakes, streams) it was frigging awesome. Took us 6
hours to get all 15 or 18 checkpoints. So extending Matt's idea into
more than 2 checkpoints is definitely something people have done and
will be interested in. anyways, thats for a later fox hunt.

A thought on location; Brackenridge Park was suggested by K5SUZ during the net Wednesday. He had participated in a multiple transmitter hunt there in the seventies and mentioned that the parking lot of Alamo stadium was a good starting point due to elevation over the entire park. Alamo as a start point is probably overkill for our needs, but the park itself has merit.

Centrally located (bracketed by 281, Hildebrand, Broadway, & Mulberry) , it’s 343 acres provides ample space to operate. Abundant oaks provide lots of shade, and the ducks swimming in the river are good entertainment. Additionally it has good things to do in the area (Zoo, Japanese Tea Garden, Witte Museum) for family members not participating in the fox hunt.

LOANER EQUIPMENT – If we end up with a large response of folks that want to play but don’t have a 2-meter HT, I have several handheld scanners that would work fine for the fox hunt. Just need to build a few extra antennas (BNC connector).

On the topic of RDF, there is a problem with getting close to a strong transmitter in that the transmitted signals actually penetrate the radio's case and it doesn't matter which way you point the antenna your S-meter is at full strength. The solution that many use is called an offset attenuator or or active attenuator. It's a pretty simple device and works by mixing the hidden transmitter's signal with a locally generated signal (typically 1, 2, or 4 MHz) which allows you to tune the hidden transmitter at a different frequency, say 4 MHz higher, that way the hidden transmitter is no longer overloading your radio.

Soo.... I'm thinking this may be a problem that we are going to run into. I've done a little research and some pricing on kits.

I've priced out building this unit as a kit (via mouser), _all_ parts needed included. Total comes out to ~$23/kit (that parts list is for 8 kits plus some extra cheap stuff).
I don't think there would be much per unit difference if we only
ordered enough for 4 kits. The only problem I can think of is that
people with SMA connectors on their radios and antennas will need
adapters, or I'll have to reprice some parts and what not. I think you
might need 2 adapters and those run about $4-5 per adapter. So if you've
got SMA you're looking at around $35-$40 total, of course the adapters
will surely be useful for other things as well, and maybe you already
have some.

There's also this offset attenuator which I think I can build for about $20 including case, and BNC connectors, etc. I haven't done a full pricing out, and some of the components are no longer around like the MFP102, but I think I can replace it with a BS170. It would require some testing to make sure the modified version works. If I have time I'll do a full price out and see what it comes out to.

Anyway, if y'all know of anything else, or have other ideas or questions, or are even interested, please let me know as I'm planning on building or buying one depending on what kind of response I get.